The present invention relates to storing various objects and more particularly to the storage of piles of sheets, for example made from corrugated cardboard in a packing manufacturing factory.
Reference will be made hereafter, solely for reasons of convenience, to this latter application, but it must not be lost from view that the invention applies to all kinds of fields where it is necessary to store various objects whatsoever with a view to the use or further treatment thereof.
In a factory manufacturing corrugated cardboard packings, very large areas are required for storing piles of cardboard sheets. These areas, which are generally situated between the corrugating machine and the machines for transforming the blanks, may be mechanized so that all handling of the loads is effected automatically without human intervention.
In its present most highly developed arrangement, the storage area is formed by a plurality of parallel and juxtaposed tracks, formed from adjacent rollers, with axes perpendicular to the direction of the tracks. These rollers are either all motor driven, or mounted free and associated with driving caterpillar tracks disposed laterally along the running tracks.
The flexibility in use of a factory requires very large storage areas. In the above-described present systems the cost of the storage area is directly proportional to this area. The investments required for constructing a large storage area are then very high. Moreover, although they are all motor driven, the rollers are only in use for a very small fraction of time, corresponding to the time for bringing the pile to the chosen position in the area and to the time for transferring it from said position to the handling apparatus. Experience has shown that for 95% of the time, the function of the rollers and the drive function of the motorization device are unused, since the piles of cardboard sheets are at rest.
Moreover, the lateral filling coefficient of said storage area depends on the dimension of the sheets and is only very rarely maximum since the width of the roller alleys and the pitch between driving tracks are chosen, as a rule, at least equal to the maximum opening of the machines supplied. When the piles have a smaller width, the result is a loss of space.
From U.S. Pat. No. 2,711,812 an installation is known for storing objects which partly overcomes this drawback. This installation comprises a plurality of horizontal and parallel beams spaced apart by a constant pitch and resting on supports, so as to define therebetween passage tracks parallel to the beams, and a plurality of mechanized handling vehicles each movable along one of the tracks, and which may be adjusted in height between a low position in which they may be positioned under a load placed on two adjacent beams and a high position in which they lift the load above the beams.
These handling vehicles are equipped with belt conveying means, extending in a direction perpendicular to that of the tracks, which allow the load to be moved transversely from one track to the next, where it is taken over by the handling vehicle associated with said next track.
Moreover, the beams are equipped with belt conveying means which allow the loads which are placed thereon to be moved longitudinally without the help of the handling vehicle.
Such an installation presents the great disadvantage of using as many handling vehicles as there are intervals between beams or tracks. Now, this number is high since the beams must be relatively close together to offer a stable seat for the loads which they support. But, as has already been mentioned, the handling vehicles form a major part in the investment costs of the storage area.
It will be further noted that in such handling vehicles the transverse conveying means which allow a load to be transferred from one track to the next are mechanized over the whole surface of the vehicle. Thus, the transporting belts are motor driven and extend over the whole upper surface of the vehicle. But this entails a consumption of energy greater than that required for moving the load.
In addition, for long loads which rest on more than two beams, several trucks must be positioned under the load so as to support it without risk of deformation or tipping.
Finally, it will be noted that according to this patent the vehicle is brought to its high position by a mechanism which bears on the chassis of the vehicle. This latter must then have a relatively massive structure capable of supporting the stresses exerted by said mechanism.